Orthodontic therapy is a specialized area of dentistry concerning the supervised treatment of malpositioned (or crooked) teeth. Generally such treatment involves the judicious application of light continuous forces to the teeth using one or more orthodontic appliances. These forces stimulate changes in surrounding bone structure, thereby gradually directing teeth to their proper locations in the oral cavity. Orthodontic therapy can provide many benefits, including ease of maintaining hygiene, improved facial appearance, as well as improved bite function.
Fixed appliances, or “braces,” represent one type of orthodontic treatment in which tiny slotted appliances, called brackets, are attached to the teeth. A resilient, U-shaped (i.e., parabolic) archwire is then placed into the slots of the brackets. When ligated to the brackets, the archwire acts as a track that guides teeth toward their proper locations during the course of treatment. In the beginning of treatment, the archwire tends to have small cross-sectional dimensions to facilitate ligation and also keep forces imparted to the teeth relatively low as the teeth unravel. In later stages of treatment, the teeth approach their target positions, allowing for progressively larger (and stiffer) wires to be used to improve the practitioner's control over the associated teeth.
Orthodontic brackets may be made from a range of different materials such as metals (e.g., stainless steel), plastics (e.g., polycarbonate) and ceramic materials such as monocrystalline and polycrystalline aluminum oxide. Archwires may also be made from a range of metal or metal alloy materials including stainless steel, titanium, and shape memory alloys such as alloys of nickel-titanium and copper-nickel-titanium.